ZyXEL Communications ZYWALL USG 20 Manual page 400

Chapter 23 IPSec VPN
Table 115 Configuration > VPN > IPSec VPN > VPN Connection > Edit (continued)
LABEL
Remove
#
Encryption
Authentication
Perfect
Forward
Secrecy (PFS)
Related Settings
Add this VPN
connection to
IPSec_VPN zone.
Connectivity
Check
Enable
Connectivity
Check
400
DESCRIPTION
Select an entry and click this to delete it.
This field is a sequential value, and it is not associated with a specific
proposal. The sequence of proposals should not affect performance
significantly.
This field is applicable when the Active Protocol is ESP. Select which
key size and encryption algorithm to use in the IPSec SA. Choices
are:
NULL - no encryption key or algorithm
DES - a 56-bit key with the DES encryption algorithm
3DES - a 168-bit key with the DES encryption algorithm
AES128 - a 128-bit key with the AES encryption algorithm
AES192 - a 192-bit key with the AES encryption algorithm
AES256 - a 256-bit key with the AES encryption algorithm
The ZyWALL and the remote IPSec router must both have at least one
proposal that uses use the same encryption and the same key.
Longer keys are more secure, but require more processing power,
resulting in increased latency and decreased throughput.
Select which hash algorithm to use to authenticate packet data in the
IPSec SA. Choices are SHA1 and MD5. SHA1 is generally considered
stronger than MD5, but it is also slower.
The ZyWALL and the remote IPSec router must both have a proposal
that uses the same authentication algorithm.
Select whether or not you want to enable Perfect Forward Secrecy
(PFS) and, if you do, which Diffie-Hellman key group to use for
encryption. Choices are:
none - disable PFS
DH1 - enable PFS and use a 768-bit random number
DH2 - enable PFS and use a 1024-bit random number
DH5 - enable PFS and use a 1536-bit random number
PFS changes the root key that is used to generate encryption keys for
each IPSec SA. The longer the key, the more secure the encryption,
but also the longer it takes to encrypt and decrypt information. Both
routers must use the same DH key group.
Select this check box to add the VPN connection policy to the IPSec_VPN
security zone. Any security rules or settings configured for the IPSec_VPN
security zone will also apply to this VPN connection policy.
The ZyWALL can regularly check the VPN connection to the gateway
you specified to make sure it is still available.
Select this to turn on the VPN connection check.
ZyWALL USG 20/20W User's Guide